Ultra-Wideband is a high-potential technique for low-power solutions in short-range wireless communications. It is therefore studied by various standards. In addition, UWB is a viable candidate for wireless body area networks or sensor networks with severe power constraints and where the communication scenario is mostly asymmetric, such as ultra-low-power sensors transmitting to a base station. A device which is particularly suited to such low-power and low to middle-rate applications thanks to low-complexity analog implementations, is e.g. an impulse radio solution (IR-UWB).
Whatever the selected architecture, synchronization is the biggest problem for IR-UWB reception. All positions are searched in order to find the location where pulses are recovered with maximal energy, and pulses must be combined correctly in order to recover data bits. Therefore, before sending the data, the transmitter has to send a preamble long enough to make the synchronization possible.
There are two main approaches for signal acquisition: optimal estimation techniques and threshold-based search strategies, Sandeep R. Aedudodla et al., “Timing acquisition in ultra-wideband communication systems”, IEEE Transactions on Vehicular Technology, 54(5):1570-1583, September 2005. Receivers relying on optimal estimators often need a full Nyquist-rate digital sampling of the incoming signal, at one Giga sample per second in the baseband as demonstrated in R. Blaquez et al., “A baseband processor for impulse ultra-wideband communications”, IEEE Journal on Solid-State Circuits, 40(9):1821-1828, September 2005. This makes such solutions more complex in terms of signal processing and puts high constraints on the ADC and its power consumption. Simpler search solutions lead to a lower performance, but at a reduced cost.